I have a unique situation that I am unable to figure out so I am going to try posting here and see if I can get some ideas. I have a 2002 trailblazer 4.2, 4x4 ,83k miles. I bought it with a previous transmission fire after it had been towed by motor home. It had an obvious burnt transmission and the harness above transmission had a burnt place in it. We replaced the engine and transmission harness then hooked a new neutral safety switch up and tried to start before purchasing another transmission. I wanted to hear it run first. It will crank but not start. Scanner shows p1271 and p1639. Fuel pump will not run during crank. The harness we used is from a 2005 trailblazer 4x4.
2002 trailblazer, cranks no start
- Thread starter vancesales
- Start date
wsweet
Member
- Sep 25, 2014
- 49
The p1271 can be from fan clutch harness or pedal assembly. The code p1639 is something the to do with the voltage out of tolerance. And I'm not sure if the 02 and 05 have different type of plugs if so and you replaced the whole engine and tranny harness with a new pcm also and didn't change the wires to the fuel it might be that
It will start with starting fluid. The fuel pump will run prime cycle then shuts off during crank. If you jump across relay and make pump run it wont make any fuel pressure. we have changed pumps with same results. we are going to change the accelerator pedal sensor this morning and see what happens. I've been told that it should start with transmission out of it as long as neutral safety switch is hooked up.
KNBlazer
Member
- Feb 8, 2012
- 811
check for a broken camshaft sensor... swap sensors from one engine to the other if so equipped on the new to you engine .... I remember a member a while back had an issue with his sensor being broken... Data has to be sent back to the PCM that it's trying to start, something is not able to send its data back....only other thing would be to check the underneath part of the engine bay fuse box for obvious damage... You're going to need a voltmeter and wiring diagram to track back ...vancesales said:
Accelerator pedal sensor did not help even though that is the code we are getting P01639. No code for cam or crank sensor but it sure sounds like a crank sensor problem . fuse box looks good underneath and to pcm all looks good the plug that goes to the crank sensor was different on the harness we used so we swapped plugs from original harness. if anyone has diagrams of pcm and engine harness that would be great?
ChrisinVictoria
Member
- Apr 26, 2014
- 53
I swapped an 03 engine into my 2002 TB. It would crank but not run. I swapped the fuel rail with injectors from my old engine and it fired right up. I don't know if it was stuck injectors or what, I suspect the donor had been sitting for several years. Did the truck sit for a long time after the fire?